THERMALITO -- While fire officials wait until it's safe to investigate the cause of a fire Thanksgiving morning at the Robert B. Robie Thermalito Pumping and Generating Plant, hazardous materials crews have been working to clean up the structure.

Also, a crew that handles emergency spills to the environment laid booms into the Thermalito Afterbay to catch oil in case it spilled into the waterway after the fire.

The inferno broke out around 7:30 a.m. Nov. 22 at the five-story structure, located about four miles west of Oroville.

Although the Department of Water Resources is the lead agency, Cal Fire-Butte County is also involved in finding the cause of the blaze.

As of Wednesday, nothing has been determined about the cause or origin because fire investigators haven't been able to get in safely.

"They're still cleaning up," said Cal Fire Capt. Scott McLean Wednesday. "We haven't been able to do anything because we've been unable to walk in."

The delay is due to the location of the fire and extreme hazard from debris and smoke residue, he said.

McLean said DWR has been handling the cleanup, dealing with oil, petroleum, insulation of wire and wire, and other substances burned in the fire.

The cleanup crew has been working with breathing equipment and special suits, he said.

"A lot of things are hazardous," he continued.

Officials have also taken precautions to protect the nearby canal and Thermalito Afterbay. The plant is near the north end of the canal between the Forebay and the Afterbay.

DWR official Nancy Vogel confirmed booms were initially set up in the canal downstream of the plant in case of a leak or spill.

"Fortunately, there was none," she said.

Monday, a crew from NRC Environmental Services was seen at the Afterbay working with booms there.

Thursday in an email, DWR spokeswoman Jennifer Iide said the booms were placed in the Afterbay to contain lubricating oil and not for other contaminants.

The booms work by acting as a floating fence to stop the flow of oil downstream, she explained.

"After the fire, there was some concern, as damage to the plant's systems was uncertain," Iide stated. "Preliminary investigations indicated that the chance of a spill was small. The boom that remains will be removed when personnel are available to remove it.

"There is now no expectation of a spill from the power plant."

McLean said the fire is thought to have started in the second floor control room, in the northwest corner of the building, and went down into the third floor. Smoke damaged the top floor, which is the only story above ground.

He said a lot of electronics burned, but neither agency has been able to estimate the cost of the fire yet.

It may take several months for officials to determine what caused the blaze.

"It's going to take some time," McLean said. "At this time, we don't know. It's a difficult situation down there. It's going to be a lengthy process to determine what took place.

"From what I've seen from pictures and what people have told me, there is significant damage."

McLean added it's an involved process because of the contaminants, which are not in the air but on the ground and in walls.

"DWR did a good job as far as making sure things (go right) in case of an emergency like this," McLean said. "They were definitely taking all the precautions."

Before the fire, electricity was generated through the plant to pump water for the state water project. It worked in tandem with the Hyatt Power Plant at Oroville Dam, several miles east.

Now, the Robie facility is completely shut down and without power, Iide said.

Iide said a hazmat crew is out at the site doing structural analysis and cleanup, and officials are collecting maintenance data, interviewing crews and having forensics experts go to the scene to try to assess exactly where the fire started and what caused it.

Iide estimated it could take up to five months to complete an investigation.